1. Field
One or more embodiments of the present invention relate to a positive active material, and a positive electrode and lithium battery including the positive active material.
2. Description of the Related Art
Recently, lithium batteries have attracted attention as a power source for portable, small electronic devices. As lithium batteries use an organic electrolytic solution, lithium batteries have discharge voltages two times or greater than those of batteries using aqueous alkali solutions, and thus have higher energy densities.
A lithium battery uses materials that allow intercalation and deintercalation of lithium ions as the negative electrode and the positive electrode. A lithium battery is prepared by charging an organic electrolytic solution or a polymer electrolytic solution between the positive electrode and the negative electrode, and generates electrical energy by oxidation and reduction reactions during the intercalation and deintercalation of lithium ions at the positive electrode and the negative electrode.
LiCoO2 is mainly used as a positive active material for lithium batteries. However, LiCoO2 is expensive to prepare, and is relatively unstable during preparation. Accordingly, positive active materials may use nickel or manganese complex oxides as materials to replace or supplement LiCoO2.
With regard to nickel-based complex oxides, in order to increase capacity per unit volume of the lithium battery, the atomic percentage of nickel is increased, or the density of the positive active material is increased. However, there is still a need for a positive active material that is thermally stable and has good capacity as well as improved filling density.